Neurons carry information in the form of electrical impulses. Scientists classify them by shape, function, or branch diameter.
Neurons classified by shape look at the number of poles or points where a neuron branch meets the cell body. Neurons are termed unipolar, bipolar, or multipolar.
Neurons can also be conveniently grouped according to function : sensory neurons- impulses travel from receptor organs to the central nervous system, motor neurons - impulses travel from the central nervous system to muscles and glands, interneurons - transmit impulses from neuron to neuron.
Finally neurons can be classified by branch diameter or thickness of myelin encompassing the axon. They are ranked either A, B, or C with A being the thickest and C the thinnest. This thickness diameter correlates with the rate at which impulses are transmitted. The A ,or thickest, neurons carry impulses at a fast rate whereas the C, or thinnest, neurons carry impulses at the slowest rate.
The neurons with the slower transmission rates have the thinnest branch diameters.